The invention had the object of finding novel compounds having valuable properties, in particular those which can be used for the preparation of medicaments.
The present invention relates to compounds and to the use of compounds in which the inhibition, regulation and/or modulation of signal transduction by protein kinases, in particular immune-modulatory or stress response kinases, furthermore to pharmaceutical compositions which comprise these compounds, and to the use of the compounds for the treatment of kinase-induced diseases. Because protein kinases regulate nearly every cellular process, including metabolism, cell proliferation, cell differentiation, and cell survival, they are attractive targets for therapeutic intervention for various disease states. For example, cell-cycle control, immune modulation, stress response and angiogenesis, in which protein kinases play a pivotal role are cellular processes associated with numerous disease conditions such as but not limited to cancer, inflammatory diseases, neurodegenerative diseases, chronic infections, abnormal angiogenesis and diseases related thereto, atherosclerosis, macular degeneration, diabetes, obesity, and pain.
Compounds of formula I inhibit the stress response eIF2 kinase EIF2AK4 called general control nonderepressible 2 (GCN2).
Many strategies of cancer treatment of solid tumors focus on the surgically removal of the tumor mass as far as possible and the subsequent eradication of any residual tumor cells by radiotherapy and chemotherapy with cytotoxic agents or inhibitors that target cancer cell pathways more specifically. However, the success of such approach is limited and often does not persist. This is mainly due to the narrow therapeutic window for such cytotoxic agents (specificity and side effects) and to the capability of cancer calls to adapt to the selective pressure applied by cytotoxic or other inhibitory agents. The survival of a small number of tumor (stem) cells that acquired resistance to the initial treatment can be sufficient to seed the regrowth of a tumor. These relapses are in most cases more difficult to treat compared to that of the initial tumors. As a consequence the more successful targeting of tumor cells may require targeting multiple survival and escape mechanism of tumor cells in parallel (Muller & Prendegast 2007).
Development of malignancies is accompanied by a major roll up of the cellular physiology. During this process several qualities are acquired by the cancer cells that are basis for immortalization or insensitivity to growth inhibitory signals. In addition the tumor cells also modify the interaction with the microenvironment and beyond. The latter area includes the strategies of tumor cells to escape from the immunological surveillance (Muller & Prendegast 2007). The immune surveillance limits malignant growth but also provides a selective pressure triggering the evolution of mechanisms for evading the immune response as reviewed by [Dunn et al. 2004]. Essentially it has been frequently observed that ablation of T cell immunity is sufficient to increase tumor incidence [Shankaran et al. 2001] and it is believed that immune escape is affecting tumor dormancy versus progression, promoting invasion and metastasis and negatively impacts on therapeutic response.
Several mechanistic studies discovered that immune escape has an important interface with metabolic alterations within the tumor microenvironment. Here important roles in mediating immune tolerance to antigens have been associated to the catabolism of the essential amino acids tryptophan and arginine, carried out by the enzymes indoleamine 2,3-dioxygenase (IDO) and arginase I (ARG), respectively (Bronte and Zanovello, 2005; Muller et al., 2005b; Muller and Prendergast, 2007; Munn and Mellor, 2007; Popovic et al., 2007). IDO is a single-chain oxidoreductase that catalyzes the degradation of tryptophan to kynurenine. IDO is not responsible for catabolizing excess dietary tryptophan but to modulate tryptophan level in a local environment. Elevations in tryptophan catabolism in cancer patients manifest in significantly altered serum concentration of tryptophan or catabolites and this was correlated to IDO which is commonly elevated in tumors and draining lymph nodes. According to several publications IDO over-expression is associated with poor prognosis in cancer [Okamoto et al 2005; Brandacher et al, 2006]. T cells appear to be preferentially sensitive to IDO activation, such that when starved for tryptophan they cannot divide and as a result cannot become activated by an antigen presented to them. Munn and Mellor and their colleagues, revealed that IDO modulates immunity by suppressing T-cell activation and by creating peripheral tolerance to tumor antigens (Mellor and Munn, 2004). These mechanism encompass the subversion of immune cells recruited by the tumor cell to its immediate microenvironment or to the tumor-draining lymph nodes Here the tumor antigens that were scavenged by antigen-presenting cells are cross-presented to the adaptive immune system. In addition to being directly toleragenic, mature DCs have the capacity to expand regulatory Tcells (Tregs) [Moser 2003].
Beside tryptophan catabolism the conversion of arginine is increased in a tumor-conditioned microenvironment, and numerous reports indicate a role for the activation of arginases during tumor growth and development. In tumorinfiltrating myeloid cells, arginine is converted by arginase I (ARG1), arginase II (ARG2) to urea and ornithine and oxidized by the inducible form of nitric oxide synthase (NOS2) to citrulline and nitric oxide (NO).
Increased ARG activity is frequently observed in patients with colon, breast, lung, and prostate cancer [Cederbaum 2004] correlating with the over-expression of ARG and NOS found in prostate cancers [Keskinege et al. 2001, Aaltoma et al. 2001, Wang et al. 2003]. It was shown that ARG activity in infiltrating macrophages impairs antigen-specific T cell responses and the expression of the CD3 receptor. Moreover the cumulative activity of ARG and NOS in tumor associated myeloid cells can generate inhibitory signals to antigen-specific T lymphocytes that eventually lead to apoptosis [Bronte 2003 a; 2003b].
Both, the IDO and the ARG related mechanism merge at the point of sensing the depleted concentration of the respective amino acid concentration. During amino acid deprivation, the eIF2 kinase EIF2AK4 called general control nonderepressible 2 (GCN2) is interacting with the intracellular accumulating deacylated tRNA. As a consequence the GCN2 is assumed to change from an auto-inhibited to an active conformation and further activate by auto-phosphorylation. Then the only known substrate protein eIF2a becomes phosphorylated and as a consequence the complex for translation initiation is inhibited [Harding et al. 2000,]. This diminishes the general Cap-dependent translation initiation and by this the corresponding protein production. On the other hand this induces the specific expression of stress related target genes mainly by cap-independent initiation via the activating transcription factor 4 (ATF4). By expressing the respective stress response proteins, e.g. enzymes in the in amino acid metabolism, the cell tries to compensate the particular cell stress [Wek et al. 2006]. If the stress persists, the same pathway will switch to promoting cell death via transcription of the pro-apoptotic transcription factor, CCAAT/enhancer-binding protein homologous protein (CHOP) [Oyadomari 2004]. It was shown that tryptophan starvation triggers a GCN2-dependent stress signaling pathway. In T cells altering eIF2aphosphorylation and translational initiation leading to a cell growth arrest (Munn et al. 2005). Sharma, et al. [2007] published on the direct IDO-induced and GCN2-dependent activation of mature Tregs. Analogously Fallarino et al[2006] found a GCN2-dependent conversion of CD4+CD25− cells to CD25+FoxP3+ Tregs producing IL-10 and TGFβ. Rodriguez et al. [2007] identified that activation of the GCN2 pathway via tryptophan or arginine depletion in combination with TCR signaling leads to CD3ζ chain down regulation, cell cycle arrest and anergy.
Importantly the GCN2 pathway is not only important for the tumoral immune escape but also plays an active role in modulating tumor survival directly. Ye et al[2010] found that the aforementioned transcription factor ATF4 is over-expressed inhuman solid tumors, suggesting an important function in tumour progression. Amino acid and glucose deprivation are typical stresses found in solid tumours and activated the GCN2 pathway to up-regulate ATF4 target genes involved in amino acid synthesis and transport. GCN2 activation/overexpression and increased phospho-eIF2a were observed in human and mouse tumors compared with normal tissues and abrogation of ATF4 or GCN2 expression significantly inhibited tumor growth in vivo. It was concluded that the GCN2-eIF2a-ATF4 pathway is critical for maintaining metabolic homeostasis in tumor cells.
Over all the present biology makes an interference with the ARG/IDO pathway attractive for braking up the tumoral immune escape by adaptive mechanism.
The interference of GCN2 function is here of particular interest as it is a merging point of the two pathways, the IDO and ARG, as well as it provides additional opportunities to impede with the tumor metabolism directly.
Several pathway inhibitors are already considered as immune modulators. These inhibitors address mainly the enzymatic function of the IDO or ARG proteins (Muller and Scherle, 2006). The application of the arginase inhibitor, N-hydroxy-nor-L-Arg blocks growth of s.c. 3LL lung carcinoma in mice [Rodriguez 2004]. The NO-donating aspirins like NCX 4016 (2-(acetyloxy)-benzoic acid 3-(nitrooxymethyl) phenyl ester) have been reported to interfere with the inhibitory enzymatic activities of myeloid cells. Orally administered NO aspirin normalized the immune status of tumor-bearing hosts, increased the number and function of tumor-antigen-specific T lymphocytes, and enhanced the preventive and therapeutic effectiveness of the antitumor immunity elicited by cancer vaccination (DeSanto 2005).
The substrate analogue 1 methyl-tryptophan (1 MT) and related molecules have been used widely to target IDO in the cancer context and other settings. Studies by Friberg et al. (2002) and Uyttenhove et al. (2003) demonstrated that 1 MT can limit the growth of tumors over-expressing IDO. However 1 MT was unable to elicit tumor regression in several tumor models, suggesting only modest antitumor efficacy when IDO inhibition was applied as a monotherapy.
In contrast, the combinatory treatment with 1 MT and a variety of cytotoxic chemotherapeutic agents elicited regression of established MMTV-neu/HER2 tumors, which responded poorly to any single-agent therapy [Muller et al 2005a]. Immunodepletion of CD4+ or CD8+ T cells from the mice before treatment abolished the combinatorial efficacy observed in this model, confirming the expectation that 1 MT acted indirectly through activation of T cell-mediated antitumor immunity. Important evidence that IDO targeting is essential to 1 MT action was provided by the demonstration that 1 MT lacks antitumor activity in mice that are genetically deficient for IDO [Hou et al., 2007]
The inhibition of GCN2 would enable to combine the two pathway branches of amino acid starvation induced immunoediting and would reduce the options for the tumor to circumvent the inhibition of either branch. Moreover, as detailed above, the GCN2 inhibition provides the opportunity for interfering with the tumor metabolism at the same time what may enhance the efficacy of a monotherapy or a combination therapy with other anticancer approaches.
As mentioned above, the eIF2 kinase GCN2 is activated by interacting with deacylated tRNA that is accumulating as direct consequence of nutritional deprivation stress. Other cellular stress factors like UV irridation, redox stress or proteasome inhibition can induce GCN2 activation indirectly [Wek et al 2006]. In all known cases eIF2a becomes phosphorylated and this induces the specific expression of stress related target genes mainly by cap-independent initiation via the activating transcription factor 4 (ATF4). Mitsuda et al (2007) showed that presenilin-1 is induced by activating transcription factor 4 (ATF4), regulated by GCN2. Accumulation of amyloid-β (Aβ), which is generated from amyloid precursor protein by γ-secretase, in cerebral cortex is common and critical incident in Alzheimer disease. Specifically, presenilin is an essential for γ-secretase activity. Ohata et al. (2010) describe a role of GCN2-eIF2α-ATF4 signaling in the regulation of γ-secretase activity in autophagy impaired cells: The impairment of the autophagy-lysosomal system may cause amino acid imbalance in the cell because autophagy is required for maintenance of amino acid level. The autophagy-lysosomal system is discussed as a vital modulator of γ-secretase activity through GCN2, leading to Aβ accumulation in autophagy deterioration, which may be a possible therapeutic target for reducing Aβ production. γ-Secretase plays an important role in the development of Alzheimer disease (AD). γ-Secretase activity is enriched in autophagic vacuoles and it augments amyloid-β (Aβ) synthesis.
Senile plaques are primarily composed of β-amyloid peptides (Aβ) derived from amyloid precursor protein (APP) that has undergone proteolytic processing by β-secretase (BACE-1) and γ-secretase. O'Connor et al.(2008) found that BACE-1 levels are translationally increased by phosphorylation of eIF2α.
Inhibition of GCN2 under such disease conditions that promote activation of γ-secretase or induction of BACE-1 with consequence of accumulation of Aβ and plaque formation in the brain would provide a valuable avenue to temper or even stop the progression of neurodegenerative diseases.
It was described that persistent, not acute, parasite or viral infections are associated to the establishment of immune privileged conditions of even immune competent host towards the infectious organism or particles. This has been associated to the local induction of IDO expression. Makala et al (J Infect Dis. 2011 Mar. 1; 203(5):715-25) show that cutaneous Leishmania major infection stimulated expression of the immune regulatory enzyme indoleamine 2,3 dioxygenase (IDO) in local lymph nodes. Induced IDO attenuated the T cell stimulatory functions of dendritic cells and suppressed local T cell responses to exogenous and nominal parasite antigens. IDO ablation reduced local inflammation and parasite burdens, as did pharmacologic inhibition of IDO in mice with established infections. de Souza Sales (Clin Exp Immunol. 2011 Aug.; 165(2):251-63) corroborated the role of indoleamine 2, 3-dioxygenase in lepromatous leprosy immunosuppression. Boasso et al (Blood. 2007 Apr. 15; 109(8):3351-9) found that HIV inhibits CD4+ T-cell proliferation by inducing indoleamine 2,3-dioxygenase in plasmacytoid dendritic cells and that in vitro inhibition of IDO results in increased CD4(+) T-cell proliferative response in PBMCs from HIV-infected patients
Inhibitor drugs of the IDO/GCN2 pathway could be used to enhance host immunity to chronic and persistent infections.
In particular, the present invention relates to compounds and to the use of compounds in which the inhibition, regulation and/or modulation of signal transduction by GCN2 plays a role.
The synthesis of small compounds which specifically inhibit, regulate and/or modulate signal transduction by immune-modulatory or stress response kinases in particular GCN2, is therefore desirable and an aim of the present invention.
Moreover, aim of this invention is the synthesis of new compounds for the prevention and treatment of neoplastic malignancies including, but without being limited to, solid tumor cancers, cancers of the lymphatic or blood system, of neurodegenerative diseases and chronic infections.
It has been found that the compounds according to the invention and salts thereof have very valuable pharmacological properties while being well tolerated.
The compounds of the formula I can furthermore be used for the isolation and investigation of the activity or expression of GCN2. In addition, they are particularly suitable for use in diagnostic methods for diseases in connection with unregulated or disturbed GCN2 activity.
Compounds of formula I can also inhibit tyrosine kinases FMS (CSF1R), GSK3α, GSK3β, FLT3 or FLT4 or combinations of these kinases, preferentially in addition to inhibitory activity towards GCN2.
Fms-like tyrosine kinase 3 (FLT3), which is also known as FLK-2 (fetal liver kinase 2) and STK-I (stem cell kinase 1), plays an important role in the proliferation and differentiation of hematopoietic stem cells. FLT3 receptor kinase is expressed at very high levels on the cells of more than 80% of myelogenous patients and of a fraction of acute lymphoblastic leukemia cells. Furthermore, the enzyme can also be found on cells from patients with chronic myelogenous leukemia in lymphoid blast crisis. It has been reported that FLT3 kinase is mutated in 30% of acute myeloid leukemia (AML) and in a subset of acute lymphoblastic leukemia (ALL) as well (Gilliland et al, Blood 100, 1532-1542 (2002); Stirewalt et al., Nat. Rev. Cancer, 3, 650-665 (2003). Activating mutations in FLT3 mutations have been associated with a poor prognosis (Malempati et al., Blood, 104, 11 (2004). FLT3 inhibitors are being developed and some have shown promising clinical effects against AML (Levis et al Int. J. Hematol, 52, 100-107 (2005).
It has been reported that some of small-molecule FLT3 inhibitors are effective in inducing apoptosis in cell lines with FLT3-activating mutations and prolonging survival of mice that express mutant FLT3 in their bone marrow cells (Levis et al, Blood, 99, 3885-3891 (2002); Kelly et al, Cancer Cell, 1, 421-432 (2002); Weisberg et al, Cancer Cell, 1, 433-443 (2002); Yee et al, Blood, 100, 2941-2949 (2002).
US patent application 20090054358 describes Flt3 inhibitors for immune suppression and in particular for the treatment of immune related disorders like organ rejection, bone marrow transplant rejection, non-myeloablative bone marrow transplant rejection, ankylosing spondylitis, arthritis, aplastic anemia. Behcet's disease, type 1 diabetes mellitus, graft-versus-host disease, Graves' disease, autoimmune hemolytic anemia, Wegener's granulomatosis, hyper IgE syndrome, idiopathic thrombocytopenia purpura, rheumatoid arthritis, Crohn's disease, multiple sclerosis, Myasthenia gravis, psoriasis, and lupus, among other autoimmune diseases. Flt3 Inhibitors might also be used to treat neurological disorder as neurodegenerative disease, for example a disease caused by axonal degeneration. Neurodegenerative diseases include, for example, multiple sclerosis; demyelinating core disorders, such as multiple sclerosis, acute transverse myelitis without being limited thereto.
Scott et al (Bioorg. Med Chem Let. (2008) 18 (17) p4794) describe CSF-1R inhibitors for the treatment of cancer. CSF-1R is a member of the class III receptor tyrosine kinases. Colony stimulatory factor 1 (CSF-1), also known as macrophage/monocyte colony stimulatory factor (M-CSF), binds to CSF-1R, resulting in dimerization, autophosphorylation, and activation of signal transduction.1 CSF-1/CSF-1R signaling is essential for normal monocyte development. In cancer, pro-tumorigenic macrophages have been identified and linked to poor prognosis in breast, ovarian, and prostate cancers. Elevated levels of CSF-1 and CSF-1R have been reported in several tumor types, including breast, ovarian, and endometrial cancers, and have also been linked to invasion and metastasis. Inhibition of CSF-1R activity could therefore have multiple effects on the tumor through reduction in the levels of tumor-associated macrophages (TAMs) and have direct effects on the tumor itself (C. E. Lewis, J. W. Pollard, Cancer Res., 66 (2006), p. 605; I. Bingle, N. et al., J. Pathol., 196 (2002), p. 254; B. M. Kacinski, Ann. Med., 27 (1995), p. 79; E. Garwood et al. J Clin Oncol 26: 2008).
Su J L et al. (Cancer Cell. 2006 March; 9(3):209-23) report that the VEGF-C/Flt-4 axis promotes invasion and metastasis of cancer cells. Flt-4, a VEGF receptor, is activated by its specific ligand, VEGF-C. The resultant signaling pathway promotes angiogenesis and/or lymphangiogenesis. VEGF-C/Flt-4 axis enhances cancer cell mobility and invasiveness and contributes to the promotion of cancer cell metastasis. Examination of tumor tissues from various types of cancers revealed high levels of Flt-4 and VEGF-C expression that correlated closely with clinical metastasis and patient survival. Inhibition of FIt-4 kinase could reduce the invasive capacity in different types of cancer
Combining the inhibitory specificity towards GCN2 with that towards FMS (CSF1R), FLT3 or FLT4 or combinations of these kinases can be of particular advantages for the treatment of neoplastic malignancies at different disease stages. It could combine the effects of stimulating the immune response towards cancer/tumor cells, to reduce the levels of tumor-associated macrophages as well as the invasive capacity of cancers for metastasis formation. In a further aspect the combination of inhibitory activities on GCN2 particularly with inhibition of FLT3 could be advantageous for the treatment of neurodegenerative disorders as it could synergize suppressive effects on inflammatory processes with the modulation of protein deposites generation in the brain. In another aspect the combination of inhibitory activities on GCN2 particularly with inhibition of FLT3 could provide advantages for modulating the immune response to treat immune related disorders and inflammatory or autoimmune diseases.
In a further embodiment the present invention specifically relates to compounds of the formula I which inhibit, regulate and/or modulate signal transduction by GCN2, FMS (CSF1R), GSK3α, GSK313β, FLT3 or FLT4 or combinations of these kinases, to compositions which comprise these compounds, and to processes for the use thereof for the treatment of diseases and complaints that are -induced or modulated by GCN2, FMS (CSF1R), GSK3α, GSK3β, FLT3 or FLT4 or combinations of these kinases.
Further aim of this invention is the synthesis of new compounds for the prevention and treatment of neoplastic malignancies including, but without being limited to, solid tumor cancers, cancers of the lymphatic or blood system, of neurodegenerative diseases, immune related disorders like arthritis, psoriasis, lupus, multiple sclerosis or other autoimmune diseases as well as chronic infections.
The compounds of the formula I can furthermore be used for the isolation and investigation of the activity or expression of GCN2, FMS (CSF1R), GSK3α, GSK3β, FLT3 or FLT4. In addition, they are particularly suitable for use in diagnostic methods for diseases in connection with unregulated or disturbed GCN2, FMS (CSF1R), GSK3α, GSK3β, FLT3 or FLT4activity. The host or patient can belong to any mammalian species, for example a primate species, particularly humans; rodents, including mice, rats and hamsters; rabbits; horses, cows, dogs, cats, etc. Animal models are of interest for experimental investigations, providing a model for treatment of human disease.
The susceptibility of a particular cell to treatment with the compounds according to the invention can be determined by in vitro tests. Typically, a culture of the cell is combined with a compound according to the invention at various concentrations for a period of time which is sufficient to allow active agents such as anti IgM to induce a cellular response such as expression of a surface marker, usually between about one hour and one week. In vitro testing can be carried out using cultivated cells from blood or from a biopsy sample. The amount of surface marker expressed are assessed by flow cytometry using specific antibodies recognising the marker.
The dose varies depending on the specific compound used, the specific disease, the patient status, etc. A therapeutic dose is typically sufficient considerably to reduce the undesired cell population in the target tissue while the viability of the patient is maintained. The treatment is generally continued until a considerable reduction has occurred, for example an at least about 50% reduction in the cell burden, and may be continued until essentially no more undesired cells are detected in the body.
For identification of a signal transduction pathway and for detection of interactions between various signal transduction pathways, various scientists have developed suitable models or model systems, for example cell culture models (for example Khwaja et al., EMBO, 1997, 16, 2783-93) and models of transgenic animals (for example White et al., Oncogene, 2001, 20, 7064-7072). For the determination of certain stages in the signal transduction cascade, interacting compounds can be utilised in order to modulate the signal (for example Stephens et al., Biochemical J., 2000, 351, 95-105). The compounds according to the invention can also be used as reagents for testing kinase-dependent signal transduction pathways in animals and/or cell culture models or in the clinical diseases mentioned in this application.
Measurement of the kinase activity is a technique which is well known to the person skilled in the art. Generic test systems for the determination of the kinase activity using substrates, for example histone (for example Alessi et al., FEBS Lett. 1996, 399, 3, pages 333-338) or the basic myelin protein, are described in the literature (for example Campos-González, R. and Glenney, Jr., J. R. 1992, J. Biol. Chem. 267, page 14535).
For the identification of kinase inhibitors, various assay systems are available. In scintillation proximity assay (Sorg et al., J. of. Biomolecular Screening, 2002, 7, 11-19) and flashplate assay, the radioactive phosphorylation of a protein or peptide as substrate with γATP is measured. In the presence of an inhibitory compound, a decreased radioactive signal, or none at all, is detectable. Furthermore, homogeneous time-resolved fluorescence resonance energy transfer (HTR-FRET) and fluorescence polarisation (FP) technologies are suitable as assay methods (Sills et al., J. of Biomolecular Screening, 2002, 191-214).
Other non-radioactive ELISA assay methods use specific phospho-antibodies (phospho-ABs). The phospho-AB binds only the phosphorylated substrate. This binding can be detected by chemiluminescence using a second peroxidase-conjugated anti-sheep antibody (Ross et al., 2002, Biochem. J.).
Moreover, compounds of formula I inhibit GSK3α and GSK3β (glycogen synthase kinase-3 alpha and beta).
GSK3 inhibitors inhibit breast cancer cell growth and thus offer an innovative approach for breast cancers resistant to hormone-bases therapy (H. M. Kim et al., PLoS One, 2013; 8(4):e60383).
Antimyeloma activity of GSK3 inhibitors is reported by C. Fionda et al., J. Immunol. 2013 Jun. 15; 190(12):6662-72).
Anticolon cancer activity of GSK3 inhibitors is reported by E. Grissilli et al., Clin. Cancer Res. 2013 Jul. 15; 19(14):3820-31.
Antimyeloma activity of GSK3α and GSK3β inhibitors is reported by S. V. Madhunapantula et al., Pigment Cell Melanoma Res. 2013 Aug. 19doi: 10.1111/pcmr.12156.
GSK3 has been implicated in various diseases such as diabetes, inflammation, cancer, Alzheimer's and bipolar disorder. GSK3 negatively regulates insulin-mediated glycogen synthesis and glucose homeostasis, and increased expression and activity of GSK3 has been reported in type II diabetics and obese animal models (Geetha Vani Rayasam et al., British Journal of Pharmacology (2009), 156, 885-898).